The present invention generally relates to electrical motors and more particularly to a motor having the capability to detect its rotational movement.
Electric motors are primarily used to drive fans for engine cooling systems in motor vehicles at the present time and most modem vehicles have a sophisticated in-board engine control unit microprocessor (ECU) that is used to monitor and control the operation of the motor vehicle engine. With the increased sophistication in the operation and control of motor vehicles, it is very desirable to provide an input signal that is indicative of the speed of operation of an engine cooling fan to the ECU so that a diagnostic monitoring and control can be accomplished. The speed of an engine cooling fan can be determinative of an overload condition that may cause a stall of the cooling fan that in turn can cause damage to the cooling fan motor. Such an overload condition can be caused by any number of outside agencies, such as ice or snow pack, or a stick or other debris interfering with the rotation of the fan. It is therefore desirable to monitor the speed of operation of the engine cooling fan in a reliable manner that is not detrimentally affected by large temperature variations.
Accordingly, it is a primary object of the present invention to provide an improved motor that has rotational movement detection capability that is easily implemented, inexpensive and reliable in its operation
A corollary object lies in the provision of the apparatus not requiring any appreciable redesign of motor components or significant changes in the manufacturing process of such motors.
Another object is to provide such an improved motor that utilizes a small unobtrusive magnet that can be placed at various locations on the armature assembly, including the commutator of the motor without affecting the design of the armature or other components of the motor. The motor also includes a sensor that can be easily installed on the brush card that is installed within the housing of the motor near the commutator thereof.
Still another object of the present invention lies in the provision of using a conventional Hall effect sensor that is attached to the brush card and which can be positioned in close proximity to a magnet installed on the armature at one of various locations and which is adapted to produce a single pulse per revolution that can be forwarded to the ECU indicating the speed of operation of the fan.
Another object of the present invention lies in the provision for setting the small magnet in the resin during the resin molding process of the commutator.
These and other objects will become apparent upon reading the following detailed description, while referring to the attached drawings.